Research on Circulating Current Characteristics and the Vibration Mechanism on the GIS Enclosure

Mechanical faults of Gas Insulated Switchgear (GIS) often occurred, which may cause serious losses. it's of great significance to detect vibration signal for condition monitoring and fault diagnosis of GIS. Firstly, the characteristics of circulating current in the enclosure of GIS were analyzed in this paper, based on the electromagnetic inductive theorem. It was shown that the circulating current of three phase in one tank type GIS was different from that of three-phase sub-aspect type GIS, resulting in the difference of vibration between the two structures. Secondly, the vibration mechanism of GIS was researched from two aspects of electromagnetic force and magnetostriction, and the natural frequency of GIS was also studied. The vibration frequency of operating GIS was about 100Hz under normal condition, while vibration signal of iron core equipment contained a lot of higher harmonic components besides the 100Hz component due to non-linearity of iron core material. Lastly, the mechanical vibration characteristic of GIS in service was detected and researched based on a developed diagnosis system, we could see that vibration frequency of operating GIS was about 100Hz under normal condition, which was consistent with theoretical analysis.